Plastic closure caps, with an anti-tamper strip connected to the cap by numerous connecting ribs, are increasingly successful with consumers. With such closure caps, an anti-tamper strip is formed in such a way that it is fastened to the neck of the container either through heat shrinking around the container neck, through an interlocking engagement with the neck, or through shaping onto corresponding beads, cams or into undercuts on the container neck. When the closure cap is opened for the first time, a resistance caused by the anti-tamper strip's connection to the container neck results in a tearing of at least some of the connecting ribs. In this way, the initial opening of the closure cap is demonstrated and tamper evidence is achieved.
With some anti-tamper strip closure caps, a vertical predetermined breaking line (or numerous vertical predetermined breaking lines) is also provided on the antitamper strip itself, in addition to the connecting ribs. Closure caps are already known not only in the form of screw caps with internal threads, but also in the form of snap caps and caps with other kinds of attachment onto the container neck (for example, bayonet-type engagement).
One embodiment of such a closure cap is described in European Patent No. 154 603. A screw cap with a so-called mechanical anti-tamper strip is shown there which, with numerous holding cams and a bead on the anti-tamper strip, snaps over a complementary bead on the container neck when attached for the first time. The anti-tamper strip is permanently attached to the screw cap on one side by a rib.
The anti-tamper strips of the closure cap embodiment described in European Patent No. 154 603, as well as the other types and derivations of the kinds of closure caps mentioned above, require further improvement. One problem of such known closure caps is that the connecting ribs must, on the one hand, be sufficiently firm and capable of bearing a load that they are not torn or damaged through routine handling, upon ejection from an injection mold, during storage in large containers, when screwed onto the bottle, when snapped over a bead on the container, or when heat shrunk onto the container. On the other hand, each connecting rib must be extremely sensitive to all kinds of tension loading in order to tear as promptly as possible when unscrewing of the closure cap from the bottle is commenced for the first time. Only in this way can such closure caps reliably fulfill their tamper evident function. These contradictory demands are difficult to realize, and are especially difficult to achieve in the case of mechanical anti-tamper strips. When closure caps having mechanical tamper evident strips are screwed onto the bottle a relatively high loading is exerted on the connecting ribs as the anti-tamper strip snaps over the complementary bead on the bottle or the container.
The present invention serves the purpose of avoiding these known disadvantages, especially therefore to create a closure cap of the type as described above, which on the one hand properly fulfills its function as an anti-tamper strip, i.e. thus tears quickly and reliably during opening, and yet on the other hand exhibits sufficient stability to withstand the entire production and handling procedure.